Journal of Insect Physiology

The Mediterranean fruit fly (medfly) (Ceratitis capitata (Wiedemann, 1824) is a major agricultural pest, and egg desiccation is a critical constraint during handling and mass-rearing, as even short periods without moisture may compromise developmental success and downstream adult performance. The Wolbachia-medfly symbiosis is a relatively recently established artificial association, generated less than three decades ago using Rhagoletis cerasi as the Wolbachia donor. In this study, we evaluated the effects of egg-stage desiccation on developmental success and subsequent adult performance in three medfly lines differing in Wolbachia status: the uninfected Benakeion line, the wCer2-infected 88.6 line, and the wCer4-infected S10.3 line. Eggs were exposed to desiccation for 0-24 h at 4-h intervals before transfer to larval diet, and hatching, pupation, and adult emergence were recorded. We additionally assessed adult survival under stress for flies emerging from the 0, 8, and 10 h egg-desiccation treatments. Under control conditions, Benakeion showed the highest hatching and developmental recovery, S10.3 the lowest, and 88.6 intermediate performance. Across all strains, short desiccation exposures were comparatively well tolerated, whereas prolonged exposure sharply reduced hatching, pupation, and adult emergence, with the clearest decline at 20-24 h. Strain-dependent differences were expressed mainly at the hatching stage, while later developmental transitions were more similar among strains once larvae had hatched. In the adult follow-up, strain, rather than moderate egg-stage desiccation, was the main determinant of short-term survival and survival under extreme stress, with S10.3 again showing the weakest performance. These results indicate that Wolbachia-associated fitness costs in medfly are strain dependent and that egg-stage desiccation primarily acts at the embryonic bottleneck. Beyond providing insight into the Wolbachia-medfly artificial symbiosis, our findings are directly relevant to egg-handling and strain-evaluation protocols in medfly mass-rearing systems.

Iron is an essential nutrient for all types of organisms, including insects and the microbes that infect them. We predicted that insects fed an iron-supplemented diet would accumulate more iron in their hemolymph, and, because infectious microbes acquire iron from their hosts, that this extra iron would increase the severity of bacterial infections. To test this hypothesis, we studied the effects of dietary iron supplementation on infection outcomes in Manduca sexta (tobacco hornworm). Larvae were fed an artificial diet, with or without antibiotics, or the same diets supplemented with 10 mM iron. Control and iron-treated larvae were inoculated with non-pathogenic Escherichia coli or the entomopathogenic Enterococcus faecalis, and bacterial load and larval survival were measured. We found that dietary iron supplementation increased the iron content of hemolymph by approximately 20 fold; however, contrary to our prediction, this increase in iron did not result in an increase in the bacterial load of either E. coli or E. faecalis. The effect of iron supplementation on survival was more complicated. As expected, for larvae inoculated with nonpathogenic E. coli, iron supplementation had no effect. For larvae inoculated with E. faecalis, the effect of iron supplementation depended on whether antibiotics were present in the diet. Without antibiotics, iron supplementation prolonged larval survival; with antibiotics, iron supplementation decreased larval survival. The results of this study do not support the hypothesis that dietary iron supplementation increases infection severity in M. sexta. Instead, the results support the viewpoint that the relationship between dietary iron and infection outcome is complex.

Seasonal variation in day length provides a reliable cue that allows insects to anticipate upcoming environmental challenges. Here, we demonstrate that photoperiod induces pronounced, sex-specific immune priming in the linden bug Pyrrhocoris apterus. Females exposed to short-day, diapause-inducing conditions exhibited broadly enhanced immune activity compared with long-day females, whereas immune parameters in males were largely unaffected by photoperiod. Short-day females showed increased immune cell abundance, elevated expression of immune-related genes, enhanced humoral immune activity, and increased resistance to bacterial infection. Importantly, photoperiod-induced immune priming depended on a functional m-cryptochrome gene, linking seasonal immune regulation to the photoperiodic timer. Consistent with laboratory results, females collected under natural short-day conditions also displayed enhanced immune parameters despite increased environmental variability. Together, our findings identify photoperiod as a key regulator of immune preparedness in female insects and reveal a sex-specific anticipatory immune strategy associated with seasonal timing.

Black soldier fly larvae (BSFL) have quickly become one of the most farmed animals in the world. However, little is known about how to monitor stress and welfare in these animals. The difficulty of welfare assessment is compounded by the fact that BSFL live in their feed and prefer darkness. This behaviour makes it challenging to observe potential welfare indicators without inducing stress via disturbing the larvae or moving them into the light. However, acoustic devices may be able to pick up signatures of stress in the population even while they are out of sight, allowing for remote monitoring of animals in natural conditions (in the feed and/or in the dark). Acoustic monitoring of this type has been deployed for the detection of insects in stored grains, suggesting this method holds some promise for assessing insect behavioural signatures. In this study, we aimed to identify general, acoustic signatures of stress in BSFL by recording them during exposure to two stressors (light or shaking) or in a low-stress control condition. Our data suggest there are consistent differences in the acoustic recordings of the non-stressed and stressed conditions that may indicate the animals behaviours shift consistently in response to stress. Ultimately, the data suggest acoustic monitoring may hold promise for larval behaviour and/or welfare assessment and should be further explored in response to a variety of stressors across the larval life stage.

O_LIEctotherms in thermally variable environments mediate energy expenditure through both physiological and behavioural responses. However, many studies focus on constant temperature acclimation, and few consider behaviour and physiology in unison. It is unclear how acclimation to thermal variability affects locomotory choices, activity timing, and performance across daily thermal cycles. C_LIO_LIWe investigated the effects of thermal variability in the temperate dung beetle Onthophagus taurus. Following acclimation to a low amplitude (22{degrees}C {+/-} 2{degrees}C) or a high amplitude (22{degrees}C {+/-} 10{degrees}C) temperature regime, we measured behaviour and metabolic rate across temperatures. We hypothesised that O. taurus adjusts its locomotive strategy and search window when kept in high amplitude fluctuating temperatures to reduce energy loss associated with high temperature exposure. C_LIO_LIWe found that differences in energy expenditure were determined by propensity for flight which differed between acclimation treatments, particularly at intermediate temperatures. We also found that, following acclimation to a high amplitude of thermal variability, O. taurus exhibited a greater intensity of activity over a narrower window of time, and O. taurus acclimated to a low amplitude of thermal variability showed nocturnal activity. C_LIO_LIWe then used the data to model activity through the growing season over five years. Biophysical models were built using NicheMapR Microclimate and Ectotherm functions to test the length of potential searching time across seasons, the temperatures individuals are exposed, and locomotive strategy. Model outputs showed that acclimation to higher amplitudes of thermal variability increased accumulated degree-hours of activity relative to the low variability acclimation group. Individuals acclimated to higher amplitudes of thermal variability showed greater accumulated degree-hours in spring and fall, but exhibited shorter periods of activity during summer, with the model predicting increased opportunities for flight. Comparatively, O. taurus from the low variability acclimation treatment showed increased night activity in summer but did not fly. C_LI

Nocturnal migration is a remarkable phenomenon observed in many insect species, including moths. Migratory moths are capable of maintaining precise directional orientation during migration, as demonstrated in both laboratory and field studies, suggesting that they use multiple environmental cues for orientation and navigation. Recent studies on Australian Bogong moths revealed that these animals can use stellar cues and likely the geomagnetic field (in conjunction with local visual cues) to select and maintain population-specific migratory direction. However, the underlying orientation mechanisms used by most other migratory moths are still largely unresolved. Further, it remains unclear whether migratory moths can adjust their orientation using Earths magnetic field parameters for determining their position relative to the goal (i.e. location or map information) - an ability clearly shown in some migratory birds which respond to virtual magnetic displacements by correcting their orientation (experiments when animals are exposed to magnetic cues corresponding to other geographic locations). Here, we present results from virtual magnetic displacement experiments conducted on red underwings (Catocala nupta). In addition, we tested their orientation under simulated overcast conditions and in a vertical magnetic field to get indications whether this species relies on geomagnetic or celestial cues to maintain its population-specific migratory direction. Our results show that (1) red underwings did not compensate for virtual magnetic displacement, indicating the absence of a magnetic map; (2) they remained significantly oriented in the absence of geomagnetic information, suggesting the use of a stellar compass; and (3) there was no evidence of magnetic compass orientation in absence of any visual cues.

Animals sense and integrate complex external cues to make developmental decisions that help them better survive and adapt to their natural habitats. Under environmental adversity, nematodes can enter an alternative developmental pathway to form a diapautic and stress-resistant stage, termed the dauer larvae. While dauer formation has been well characterized in Caenorhabditis elegans, how environmental factors influence analogous stages in other nematode species remains largely unexplored. This study examines how symbiotic bacteria, temperature, and pheromones affect the formation of the infective juvenile (IJ), a dauer-like stage, of the insect-parasitic nematode Steinernema hermaphroditum. In contrast to C. elegans, where dauer entry is promoted by heat, IJ development in S. hermaphroditum development is enhanced by reduced temperature. Moreover, the presence and absence of live symbiotic bacterium Xenorhabdus griffiniae functions as an ON-and-OFF switch that regulates the host IJ formation. Crude pheromone extracts from S. hermaphroditum liquid culture do not robustly induce IJ formation in a dose-responsive manner, unlike the potent pheromone-driven dauer entry observed in C. elegans. Nutrient-rich liver-kidney media that mimics host insect environment showed IJ entry induction in a pheromone-dependent manner. These data suggest that external cues, such as temperature, microbial diet, and pheromone, are perceived differently by S. hermaphroditum in comparison to that of C. elegans, reflecting species-specific adaptations to distinct ecological niches and life history strategies.

Because hypoxia and low temperature independently alter metabolism and reproductive investment, their interaction provides a tractable framework for testing whether combined stressors produce non-additive physiological and reproductive effects. Here, we investigated the single and combined effects of hypoxia and low temperature in Drosophila melanogaster across multiple genetic backgrounds. We quantified metabolic rate, thermal tolerance, body mass, fertility, oogenesis progression, and oocyte apoptosis to assess organismal responses to environmental stress. Hypoxia generally increased respiratory quotient and body mass, but its effects on thermal tolerance and fertility were highly genotype dependent. Across traits, combined stressors frequently produced responses that differed from those observed under single stressors, including reduced fertility, altered oogenesis, and changes in oocyte cell death. Importantly, these effects were not uniform: some genotypes exhibited increased oocyte production or reduced cell death under combined stress, highlighting pronounced genotype-dependent differences in stress sensitivity and reproductive allocation. Together, our results demonstrate that the interaction between hypoxia and temperature can modulate metabolic and reproductive responses in ways that are not predictable from single-stressor responses alone. These findings highlight the importance of incorporating genetic background and interacting environmental stressors when evaluating organismal tolerance and adaptive potential under ongoing environmental change.

Adult females of the two-spotted spider mite, Tetranychus urticae Koch, enter a photoperiodically induced diapause to overwinter. Diapause in T. urticae is accompanied by reproductive arrest and the orange body coloration that arises from the accumulation of astaxanthin esters. How these two traits are coordinated at the molecular level remains poorly understood. Here, we compared the proteomes of adult females reared under diapause-inducing (long-night) and non-diapause-inducing (short-night) photoperiods using liquid chromatography-tandem mass spectrometry, followed by RNA interference (RNAi) of candidate genes. The carotenoid biosynthesis enzymes phytoene desaturase (TuPDS) and lycopene cyclase/phytoene synthase (TuLCPS), both encoded by genes horizontally transferred from fungi, were more abundant in diapausing females than in non-diapausing females. RNAi of the genes encoding TuPDS and TuLCPS markedly reduced orange pigmentation as well as {beta}-carotene and astaxanthin contents, demonstrating that these enzymes are required for diapause-associated pigmentation. Our proteomic analysis further identified a single PLAT (Polycystin-1, Lipoxygenase, Alpha-toxin) domain protein, TuPLAT10, as one of the most strongly upregulated proteins in diapausing females. The PLAT domain is a lipid-binding module, suggesting a role for TuPLAT10 in lipid metabolism. In addition to the suppression of orange pigmentation, RNAi of the TuPLAT10 gene restored reproduction even under diapause-inducing conditions and selectively reduced TuPDS and TuLCPS protein levels, despite the absence of sequence similarity to their genes. We propose that TuPLAT10 acts as a lipid-allocation switch that, in response to photoperiodic information, partitions fatty acids between astaxanthin esterification and yolk lipid supply, thereby coupling reproductive arrest and carotenoid pigmentation during diapause in T. urticae.

A common form of Wolbachia-induced manipulation of host reproduction is Cytoplasmic Incompatibility (CI). In CI, Wolbachia modification of sperm results in pronounced defects in paternal chromosome condensation, replication, and segregation during the first mitotic division. Recent studies in D. simulans demonstrate that CI also induces independent and distinct later developmental defects resulting in high rates of mitotic errors during the mid-blastula transition and larval lethality. Here we show that in D. melanogaster, embryos derived from CI crosses experienced significant mitotic defects during gastrulation and increased larval lethality, both of which were eliminated in the progeny of Rescue crosses (both sexes infected). Examination of CI using females from 13 genetically distinct wild-type lines of the Drosophila Genetic Reference Panel (DGRP) revealed significant variation in the strength of the CI-induced lethality. Early embryonic pre-hatching and late larval lethal phases were uncorrelated, suggesting distinct factors influence the extent of the two lethal phases. Additionally, 3rd instar larvae and adults derived from D. melanogaster CI crosses exhibited locomotor defects that were also eliminated in Rescue crosses. These studies support a model in which Wolbachia effects on the sperm chromatin produce delayed developmental and locomotor defects, suggesting the involvement of epigenetic mechanisms. Support for this idea comes from our finding that levels of the heritable chromatin mark H3K27me1 are significantly elevated in CI-derived embryos. We conclude that the full measure of CI strength should take into account pre- and post-hatching lethality as well as locomotor defects. Together our findings suggest that the strength of these CI-induced phenotypes is governed at least in part by epigenetics and the maternal genetic background. AUTHOR SUMMARYSince the discovery of the antiviral properties of the bacteria Wolbachia, numerous strategies using this insect endosymbiont have been developed to combat vector-borne disease. While the success of these strategies relies on the rapid spread of Wolbachia through a naturally uninfected insect population, the molecular mechanisms by which Wolbachia promote their spread remain poorly defined. Current research on the primary mechanism behind Wolbachia spread, cytoplasmic incompatibility (CI), focuses on understanding the dramatic decrease in egg hatch rates that occurs when uninfected females mate with infected males. Here, we demonstrate that CI also induces substantial post-hatching larva and adult locomotor defects and lethality. In accord with these developmentally delayed defects, we show Wolbachia dramatically alter an epigenetic chromatin mark. Finally, we show that host maternal factors contribute to CI strength. Taken together, these results demonstrate that CI induces a much more expansive and developmentally delayed suite of phenotypes than previously reported.

High annual honey bee colony losses are associated with environmental and biological stressors, including virus infections. In insects, the octopamine pathway orchestrates the "fight-or-flight" response, regulating energy mobilization, temperature, and flight. We determined that sacbrood virus (SBV) infections induce expression of an octopamine receptor and enhance honey flight performance, whereas deformed wing virus (DWV) infections reduce flight performance, but how viruses interface with this pathway remained unknown. To elucidate the relationships between the octopamine response, virus infection, and flight, honey bees were infected with SBV or DWV and exposed to octopamine (OA), epinastine (EP)-an OA receptor antagonist, or both OA and EP; flight and gene expression were assessed. Pharmacologic manipulation revealed that octopamine supplementation rescued flight deficits in DWV-infected bees, but diminished performance in SBV-infected bees, while blocking octopamine receptors altered these effects. Transcriptome analyses indicated that SBV infections, and DWV infection with OA treatment, activated honey bee metabolic pathways, and that SBV infected bees had greater expression of genes involved in OA synthesis, unless treated with OA. These results provide a mechanistic explanation for virus-specific impacts on honey bee flight, which may have consequences on foraging efficiency, colony health and virus transmission.

O_LIPhenological shifts are a major ecological consequence of climate change, yet studies often focus on single life stages meaning that the potential for carryover effects between life stages remains poorly understood. Failing to account for these effects may lead to inaccurate estimates of phenological shifts, with consequences for predicted synchrony among interacting species. This is especially relevant for temperate systems where climate warming is occurring unevenly across the year. C_LIO_LIHere, we investigated how temperature experienced the previous autumn and winter (during the pupal and egg stage) influences spring phenology in the winter moth (Operophtera brumata), a herbivorous insect with distinct life stages. Using 50 years of local climate data to create five experimental temperature regimes, we first quantified phenotypic plasticity in the duration and temporal variability of pupal and egg development. We then examined how timing of adult moth emergence affects timing of offspring hatching. C_LIO_LIWe found divergent effects of temperature on different life stages; pupal development time was shortest at intermediate temperatures while egg development time decreased linearly with increasing temperature. Furthermore, phenological shifts due to the conditions experienced by the mother were carried over to influence the phenology of her offspring. While this carryover effect was partially compensated during subsequent stages, compensation decreased under warming conditions. C_LIO_LIThese results refine our understanding of the sensitivity of the annual cycle of winter moth phenology to variation in temperature with potential implications for population dynamics and interspecific interactions. Overall, our findings highlight the need to consider the impacts of warming across multiple life stages so that carryover effects can be properly accounted for. Doing so will improve predictions of phenological shifts under future climates. C_LI

The black soldier fly, Hermetia illucens, is increasingly valued in applied entomology due to its remarkable capacity to upcycle organic waste and for high nutritional value of its larvae. As a result of global expansion and domestication, the species now displays substantial genetic diversity, yet performance differences between strains remain poorly documented. This study aimed to better understand the relationship between genotype and phenotype, as well as their interaction, to support the improvement of its domestication. Five distinct strains collected from the wild by artisanal farmers or obtained from industrial farms were genetically characterized using whole genome sequencing. These analyses revealed high genetic divergence based on mitochondrial genome and SNP nuclear genome phylogeny. To assess phenotypic performance, the strains were reared on three diets differing in nutritional value: poor (alfalfa meal), intermediate (wheat bran) and rich (chicken feed) and their growth rate was assessed. At harvest, we evaluated different life history traits including survival rate, average larval mass, feed conversion ratio, substrate reduction and bioconversion rate. Statistical analyses revealed strong effects of both diet and strain (p < 0.001), but the key result was the pronounced strain x diet interaction. Performance varied drastically depending on substrate quality: some strains showed high versatility across all diets, while others performed mainly on nutrient-rich substrates or excelled in substrate degradation. In contrast, other strains displayed more specialized profiles, with marked sensitivity to fibrous diets. These contrasted reaction norms highlight that diet performance cannot be interpreted independently of the strain genetics. Overall, these findings underscore the value of preserving diverse local genetic resources and the need for improved molecular tools to guide strain selection. ImplicationThis study shows that performance of the black soldier fly depends strongly on interactions between genetic background and diet, confirming the importance of genotype-environment relationships. While results are based on a limited number of strains and substrates, the consistent strain x diet interaction suggests broader relevance for rearing systems. These findings highlight the need to integrate genomic data into phenotypic assessments. Practically, they indicate that strain selection should be tailored to substrate type to optimize productivity and efficiency. This has direct economic benefits for insect farming and waste management industries because improved strain-diet matching can enhance organic waste bioconversion and support circular economy strategies. Overall, preserving genetic diversity and developing molecular tools for strain selection are key steps toward more sustainable and efficient insect production systems of this study have implications for the development and sustainable BSF systems production.

Aedes aegypti mosquitoes transmit multiple arboviruses, but population suppression through the mass release of sterile or incompatible male mosquitoes can effectively reduce populations. These methods depend on the reliable mass-rearing of healthy, robust males that can successfully mate with wild females. The microbiota, a critical component of the larval diet, can dramatically influence life history traits relevant to mass-rearing and male quality. Here, we used axenic (microbe-free), monoxenic (inoculated with E. coli), and "laboratory community" mosquitoes (inoculated with an undefined microbiota derived from laboratory mosquitoes) to show that longevity was significantly enhanced in axenic and monoxenic males compared to laboratory community males. Moreover, monoxenic males more efficiently obtained mates in non-competitive mating scenarios compared to laboratory community males. However, microbiota treatment had no effect when males from different treatments competed for a mate. Our findings suggest that the microbiota is a key determinant of male mosquito life history with direct implications for optimizing production of males for control programs. TeaserThe microbiota of Aedes aegypti mosquitoes affects multiple male life history traits.

Adaptation to local environments enables species to thrive in diverse and challenging habitats. Steep elevational gradients provide a compelling natural adaptation laboratory, because abiotic conditions change progressively over short geographical differences. Given that elevation can strongly reshape physiology and behavior of insects, neuromodulatory systems offer a promising lens through which to examine elevation-specific adaptation. We challenged the hypothesis that adaptation to elevation involves octopaminergic signaling in honey bees (Apis mellifera), an important pollinator species occupying different elevations along East African mountains. We collected foragers from two distinct elevations at Mount Kenya (1,150 m and 1,900 m above sea level) and analyzed elevation-dependent changes in octopaminergic signaling. Tissue-specific analysis revealed a striking upregulation of all three octopamine {beta} receptor genes in the thoracic flight muscles and elevated octopamine brain concentrations at high elevation. Expression differences in the brain and fat body were rather modest. We subjected CRISPR/Cas9-mediated octopamine {beta}2 receptor knockouts to cold stress to study the function of octopaminergic signaling in thermoregulation. Loss of AmOAR{beta}2 reduced both the slope and amplitude of heating phases, indicating altered thermogenic dynamics. Together, these results identify the octopaminergic system as a central neuromodulatory regulator of thermogenic performance across elevations in honey bees. More broadly, our study highlights how modulation of conserved aminergic signaling pathways can shape physiological resilience to environmental gradients, pointing to a general mechanism by which insects adapt to changing thermal landscapes. Highlights- Bees from high and low elevation differ in expression of octopamine {beta} receptor genes and octopamine brain concentrations - CRISPR/Cas9-mediated octopamine receptor knockout alters thermogenic behavior - Octopaminergic signaling emerges as a key neuromodulator in thermal adaptation to elevation in honey bees Significance statementAnimals living along mountain gradients must cope with rapidly changing temperatures, yet the mechanisms enabling this adaptation remain poorly understood. We show that honey bees from higher elevations have increased brain octopamine levels and enhanced expression of octopamine receptors in heat-producing flight muscles. Using gene editing, we demonstrate that disrupting one key receptor alters how bees generate heat under cold stress. These findings identify octopamine signaling as a central regulator of thermogenesis and reveal a mechanism by which insects adjust to colder environments. More broadly, our results highlight how conserved neuromodulatory systems can fine-tune physiological performance, offering insight into how insects may respond to changing climates and expanding environmental extremes.

How insects transmit food odour preferences acquired during the larval stage to their offspring is unknown. Bicyclus anynana butterfly larvae can learn to prefer a banana-smelling odour, isoamyl acetate (IAA), via feeding on coated leaves, or simply via haemolymph transfusions from an IAA-fed animal, and transmit this preference to their naive offspring. Here we explore how larvae respond to different concentrations of IAA using olfaction choice tests, and how injections of different concentrations of IAA directly into the haemolymph impact odour learning and transmission of learned preferences. We find that naive larvae showed a slight preference towards low concentrations of IAA, and a slight avoidance towards higher concentrations. Injections of IAA at low concentrations directly into the haemolymph led to an increase in preference for IAA, whereas higher concentrations led to an increase in avoidance. Naive offspring inherited the odour preferences of their parents. Finally, injections of IAA at different concentrations into embryos did not alter choices made by hatched larvae. We establish that the same molecule (IAA) can illicit both a preference as well as an aversive reaction when directly injected into the haemolymph, but IAA is not directly implicated in intergenerational inheritance.

The cockroach Blattella germanica possesses panoistic ovaries, in which oocytes lack nurse cells and therefore need to rely on their own transcriptional activity to support embryogenesis. Ovarian development in this species involves the development of a single basal ovarian follicle (BOF) per gonadotropic cycle, a process strictly regulated by endocrine signals, primarily juvenile hormone and ecdysone, which act at both the transcriptional and translational levels. In addition, transcriptional activity in these ovaries is necessary for both regulating and genome protection, and at this level, PIWI-interacting RNAs (piRNAs) play an essential role. Although insect ovaries are known to be particularly rich in piRNAs, their function in ovary maturation is still not well defined. For this purpose, we characterize the piRNA expression dynamics across seven key developmental and reproductive stages, ranging from late nymphal instars to post-vitellogenic adults. piRNA expression in B. germanica shows coordinated fluctuations. Expression remains stable in previtellogenic ovaries, whereas vitellogenic ovaries show pronounced changes. Moreover, vitellogenic ovaries exhibit reduced piRNA diversity due to strong enrichment of a subset of highly expressed piRNAs. Our data show that although piRNAs predominantly map to transposable elements, particularly LINEs, there is a notable increase in gene-derived piRNAs toward the end of the cycle. Our results suggest regulatory roles of piRNAs in modulating both TEs and mRNAs during BOF maturation, likely related to changes in the follicular cell program.

Arboreal insects have developed various strategies to navigate their discontinuous habitats. Many insects, including leafhoppers, katydids, and praying mantises, exhibit the ability to actively leap across their leafy platforms and land on a distant substrate. This behavior is especially important for non-winged insects, including nymphal forms of winged insects, which cannot fly between these substrates. To make a targeted jump, an animal must first orient towards the target, estimate the target distance and angular location, and jump with the appropriate take-off speeds and angles to land on their intended substrate. In three-dimensional space, jumping from one point to another requires estimating distance, as well as azimuthal and elevational angles. Jumping insects such as mantises typically reorient their bodies on the substrate to align with the azimuthal direction of the target. This behavior effectively reduces the task to a two-dimensional problem, in which they must estimate only the distance to the target and its elevational angle. Many insects, including praying mantises, perform rhythmic lateral head movements called peering before performing a targeted jump. Although previous studies suggest that mechanisms such as motion parallax while peering are used for distance estimation, the full repertoire of behaviors that enable mantises to jump to arbitrarily located substrates remains unclear. We hypothesized that mantises have distinct behaviors for distance and elevation angle estimation, which enable them to independently modulate their take-off speeds and angles before jumping. To test this hypothesis, we developed behavioral assays in which mantises were placed on a launch platform and jumped to a target platform positioned at variable distances and angles. Using this apparatus, we filmed the jumps of Giant Asian mantis nymphs (Hierodula spp.) with high-speed videography and tracked body parts to quantify take-off speed and angle. Because mantis jumps are ballistic, their trajectories can be modeled as projectile motion. Our results indicate that mantises estimate target distance and elevation angle using two separate behavioral strategies: distance is assessed through peering maneuvers that generate motion parallax, whereas elevation angle is determined through visual fixation of the target accompanied by specific postural adjustments. By combining these behaviors, mantises modulate the magnitude and direction of propulsive force to achieve successful jumps.

The ectoparasitic mite Varroa destructor is the most significant parasite of the Western honey bee (Apis mellifera) and a major driver of colony losses worldwide. Although extensive research has focused on behavioral and physiological mechanisms of host resistance, comparatively little attention has been paid to potential phenotypic responses of the parasite itself. Here we investigated body size variation in Varroa destructor associated with varroa-resistant and non-resistant honey bee colonies across four European countries. We quantified the dorsal shield area of adult female mites from multiple colonies differing in the honey bee colonies resistance status, using standardized digital image analysis. Across geographically distant non-resistant populations, mite body size was remarkably consistent, with a median dorsal shield area of 1.47 mm2. In contrast, mites originating from varroa-resistant colonies were consistently smaller, with a median dorsal shield area of 1.37 mm2, representing an approximately 6.8% reduction in body size. This pattern was reproducible across different geographical areas, honey bee genetic backgrounds and beekeeping practices. The striking stability of mite body size in non-resistant populations contrasted with the consistent reduction observed in mites associated with resistant hosts, suggesting a host associated shift in parasite phenotype. Because body size in arthropods integrates developmental conditions, nutritional availability and resource allocation, the observed pattern may reflect altered developmental environments and selective pressures imposed by resistant hosts. Our results show a consistent morphological shift in this globally important parasite associated with resistant hosts and suggest that dorsal shield size in Varroa could serve as a new selection marker for varroa-resistant honey bee colonies.

Extreme climatic events impose considerable stress on organisms with consequences for key ecological interactions such as pollination. Because temperature directly affects metabolic processes, heat variations may also importantly influence the nutritional needs and feeding choices of animals. Here, we studied the effects of thermal stress on the nutritional choices and performances of bumblebees, using a 3D nutritional geometry design. At optimal temperature for colony development (30{degrees}C), bees successfully balanced carbohydrate, protein, and lipid collection, at levels beneficial for body weight and survival. Under cold stress (20{degrees}C), bees reduced their overall nutrient collection while selecting proportionally more carbohydrates, thereby prioritizing survival over weight gain. Under heat stress (35{degrees}C), nutrient balancing was disrupted and survival dropped. Notably however, across all temperatures, bees maintained stable lipid collection while flexibly adjusting the amount of carbohydrates and proteins, suggesting strong constraints on lipid regulation. Given the pivotal role of bees for pollination, identifying how their nutritional needs change in response to climatic conditions is of prior importance for food safety and the conservation of terrestrial ecosystems.